A large and growing number of households have pets. Studies have shown that pet owners often treat their pets as they treat close friends and relatives. Owners include pets in holiday celebrations, and often refer to themselves as their pets' parents. Such affinity is tangibly demonstrated in the rapid growth of a multibillion dollar pet industry with an increasing demand for pet products that mimic human products.
Health conscious consumers are also demanding higher quality pet food that is not only closer in ingredient quality to human food, but also looks less processed and more natural. However, conventional pet food producers seldom focus on the visual impact of pet food that heightens aesthetic appeal to a purchaser, even if they integrate advanced ingredients more commonly found in food produced for human consumption.
People prefer to consume meatballs that are moist, preferably with sauce or gravy. Studies have shown that pets also prefer meatballs with intermediate levels of moisture, but such products are difficult to find on the market. The primary reason is that human grade meat products are usually designed for relatively short shelf lives, whereas pet food is engineered to be stored (if necessary) for eighteen months after manufacturing before it is consumed, and therefore requires a substantially longer shelf life. Human grade meat products, once opened, become stale in less than a week unless refrigerated. Pet treats, however, are expected to last for up to three months after the package is opened, without refrigeration. Moisture content in food is typically correlated with freshness duration and time to spoilage, whereby the higher the moisture content the shorter the shelf life or safe consumption time frame. The delay in the storage and consumption of pet foods requires more careful ingredient selection, preservation of freshness with antioxidants, processing that avoids insects and rancidity, careful packaging and storage. Because high moisture meat products tend to spoil quickly, such products are usually sold in cans in the pet food market, and are more typical as cat food. Pet food or kibble with low moisture content (typically less than 10%), are dry and hard, and less palatable to pets. Semi-moist pet food, typically having moisture content between 15 and 30%, is very popular with animals since it has a texture and palatability that is closest to meat. However, as discussed, semi-moist pet food is difficult to store in a stable condition, without canning or refrigeration, for long periods.
In a typical process for manufacturing meatballs for human consumption, frozen meat or poultry is ground with various flavors, flours or seasoning in a batch mixer and then pumped into one end of a meatball former where, on the other end, there is a mechanism that “portions” the meat into smaller parts. An oscillating iris valve has found widespread use as a device that can form spherical meat portions. When meat is pushed through the iris valve, each cycle separates the meat into roughly spherical strips which are then either frozen directly, or cooked and then frozen. The iris valve and other comparable processes used for making human grade meatballs are more suited for batch or semi-continuous operations. They are less amenable to high volume processing which is particularly important for pet food markets because of cost considerations.
Meatballs for pet consumption are typically made using scrap portions from human grade meat products, or offal and other byproducts. They are sometimes cooked, refrigerated and freeze dried and sold into the pet food market. However, such freeze-dried meatballs for pet consumption are brittle, crumble easily, contain very little moisture, are generally expensive, and have therefore not been popular with consumers. These freeze-dried “meatballs” also have to be packaged with care because they are not shelf-stable at room temperature.
Thus, neither conventional pet food manufacturing processes nor traditional food production techniques used for human consumption can meet the requirements of cost-effectively manufacturing semi-most meatballs products that remain shelf stable for long periods without refrigeration. Furthermore, there is no commercially viable method for producing such meatballs for animal consumption in a continuous manufacturing process, in high volumes, using either fill and form (mold) plates or extrusion techniques.